Transitions in the Mechanism of Material Removal in Abrasive Wear of Alumina

The mechanisms of material removal in abrasive wear are investigated by scratching a fine grain alumina with a diamond indenter. Subsurface damage is examined as a function of load and number of passes using a bonded-interface sectioning technique together with microscopy. Scratching produces classical lateral and median cracks extending from the plastic zone beneath the contact area. Damage within the plastic zone is distributed in nature taking the form of intragrain twin/slip bands and intergranular microcracks. Repeated scratching causes damage accumulation in the material beneath the sliding contact area. After a critical number of passes, a transition is observed from a damage accumulation process to a material removal process that involves mainly grain dislodgement. As the number of passes is increased at large loads, the removal process exhibits a second transition from grain dislodgement to a more severe wear process by lateral crack chipping.